I make a very simple Egyptian lentil soup - grated onion, red lentils, added to pot of boiling water. Cook for ~ 45 minutes. Pepper, a little salt, a little ground cumin and a squeeze of lemon. Give it a light mix with the stick blender (I don't want it completely pureed). I like all of the stuff (carrots, ham hock, etc.) in split pea soup, but for lentil soup my taste buds dictate that less is more.